The invention relates to a method for heat and humidity exchange between two air streams, one of which being hot and humid, at least during a first part of the year, wherein a first of said air streams is fed from the interior of a building to the ambient air and a second of said air streams is fed from said ambient air to the interior of said building, whereby said first air stream is cooled and thereafter transferred through a heat exchanger, whereupon it is transferred to a heater and thereafter transferred through a dehumidifier before being exhausted to the ambient air, whereas said second air stream is transferred through said dehumidifier and thereafter through said heat exchanger, whereupon it is cooled in a cooling device before being transferred into the interior of said building.
The invention relates also to an apparatus for heat and humidity exchange between two air streams, one of which being hot and humid, at least during a first part of the year, wherein a first of said air streams is adapted to be fed from the interior of a building to the ambient air and a second of said air streams is adapted to be fed from said ambient air to the interior of said building, said apparatus comprises a housing, divided into first and second compartments, means for transportation of the two air streams separately in said compartments, a device for cooling and humidification of the first air stream, a sensible heat exchanger for exchange of heat between the two air streams, a heater for heating said first air stream, and a dehumidifier for drying said second air stream, wherein said first air stream is adapted to be transferred through said dehumidifier for regenerating said dehumidifier.
Apparatuses and methods for heat and humidity exchange between two air streams are known. Such apparatuses and methods are used for improving the indoor air in, for instance, small houses and buildings, i.e. to cool and to dry the outdoor air which is fed into a building during the summer and to heat and humidify said air during the winter before said air is transferred into the building.
However, there is a problem when the outdoor air is hot and humid, i.e. when the temperature is above 35xc2x0 C., and the content of water in the outdoor air is larger than 11 g/kg air, since the known apparatuses can not treat such air in the proper way.
Also, there is a problem with the energy consumption, which is often quite high. The energy is used to either regenerate a dehumidifier during the summer or to heat the supply air during the winter. Moreover, the production of energy may result in air pollution, and especially in undesired outlet of CO2.
Therefore, it would be desirable to provide a method and an apparatus by which it is possible to save energy.
The object of the present invention is to eliminate the above-mentioned drawbacks and to provide a method and an apparatus which will operate under the above conditions and by which it is also possible to minimize the energy consumption.
According to a first aspect of the invention this object is achieved in that said second air stream, before being fed to said dehumidifier, is caused to exchange heat and humidity with said first air stream before the latter is fed into said heat exchanger.
According to a second aspect of the invention this object is achieved in that an enthalpy exchange device is provided in said housing and adapted to treat said second air stream and said first air stream for exchange of heat and humidity between said air streams, before said second air stream is transferred through said dehumidifier and said first air stream is transferred through said humidifier, respectively.